Excess moisture within the root zone due to the shallow water table is a leading cause of crop loss in Manitoba. In this study, the ability of the DRAINMOD model to predict water table depth (WTD) in clayey soil was evaluated using measured field data from the 2019 and 2020 canola-growing seasons in Arborg, Manitoba, Canada. Statistical analysis and graphical plots showed close agreement between the measured and simulated WTD with an overall coefficient of determination (R²), root mean square error (RMSE), mean average error (MAE) and mean bias error (MBE) of 0.93, 9.84 cm, 7.06 cm and −0.13 cm, respectively. Since the model simulation was deemed satisfactory, the model was run with 30-year historical climate data to assess the impacts of different drain spacing on canola yield. Simulation results showed that the average surface runoff increased while average drainage and relative canola yield decreased as drain spacing increased. The simulation results suggest that long-term average yield would be maximized by close drain spacing ≤ 15 m. Economic analysis showed that 10 m drain spacing would maximize the return on investment. The need for long-term simulations to develop appropriate site-specific water management strategies is demonstrated.

中文翻译：

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加拿大大草原重粘土中排水间距对油菜产量影响的 DRAINMOD 模拟

由于地下水位较浅，根区水分过多是曼尼托巴省作物损失的主要原因。在这项研究中，使用加拿大马尼托巴省阿尔堡市 2019 年和 2020 年油菜生长季节的实测现场数据评估了 DRAINMOD 模型预测粘土中地下水位深度 (WTD) 的能力。统计分析和图表显示测量和模拟 WTD 与总体决定系数 ( R ²)、均方根误差 (RMSE)、平均误差 (MAE) 和平均偏差误差 (MBE) 分别为 0.93、9.84 cm、7.06 cm 和 -0.13 cm。由于模型模拟被认为是令人满意的，该模型使用 30 年的历史气候数据运行，以评估不同排水间距对油菜产量的影响。模拟结果表明，随着排水间距的增加，平均地表径流增加，而平均排水量和油菜相对产量降低。模拟结果表明，通过紧密的排水间距≤15 m，可以最大限度地提高长期平均产量。经济分析表明，10 m 的排水间距将使投资回报最大化。证明需要进行长期模拟以制定适当的针对特定地点的水管理策略。